


Sibling Rivalry

by SesuRescue (Kigachan)



Category: Undertale (Video Game)
Genre: Bets & Wagers, Blow Jobs, Competition, Ecto-Tongue (Undertale), Multi, Sibling Rivalry, ecto-throat, established Fontcest
Language: English
Status: Completed
Published: 2017-08-04
Updated: 2017-08-04
Packaged: 2018-12-11 05:40:03
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,134
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11707953
Author URL: https://archiveofourown.org/users/Kigachan/pseuds/SesuRescue
Summary: The brothers are at it again with their shenanigans. Poor Grillby gets involved.





	Sibling Rivalry

**Author's Note:**

> Received this idea from an anon this morning and I was intrigued enough to spit some words on a google doc and here we are: 
> 
> "Sans and Papyrus have a contest of who can flirt with Grillby, who isn't with either of them, the best. Grillby either doesn't seem to realize it or he does but assumes they aren't being serious since the brothers are already in a relationship."
> 
> Little editing was done, so really sorry if any of it is weird or there are mistakes.

Grillby knew that Sans and his brother were up to something, but he wasn’t sure what.

It had all began a few days ago when Papyrus sashayed into the restaurant, dressed in a pair of cut off shorts and a crop top that was showing of wayyyy too much of his spine than what was decent. Grillby fought to keep down his rising blush as Papyrus sat down at the bar in front of him, leaning forward to give him a view down his shirt.

“Hello Grillby, how are you?” Papyrus purred.

“… I’m Fine, aren’t you…”-Grillby gestured to his crop top, which he noted had a spattered orange paint pattern on it- “Cold?”

“What? No, it’s great outside.”

Grillby looked out the window, watching the snow from a particularly bad blizzard kicking down the street. “… Right. So what brings you in?”

Papyrus sat up and stretched, kicking his leg out in the barstool next to him. “Nothing much, just wanted to see my  _favorite_  bartender.”

Grillby sputtered, his flames whipping violently around him. As if coming right in time to save him, a  **pop**  happened and Sans appeared behind Papyrus, hands in his pockets.

“wow, is it  _hot_  in here or is it just you, grillbz?”

Grillby nodded towards him. “… Hello, Sans.”

Sans climbed up on his favorite barstool, knocking over Papyrus’ leg, much to his disdain.

“SANS!”

“oops.”

Papyrus and Sans glared at each other, the atmosphere around them turning tense until Grillby cleared his throat, reminding them that they were in public.

They acquiesced, but the rest of the visit had been heated as the brothers switched off between flirting with him, leaving him flustered when they both decided to leave for the night.

Over the rest of the week both Sans and Papyrus flirted with him nonstop, and he really wasn’t sure how to handle it. Papyrus went as far as to sneak into the bar overnight, lying in wait seductively on the bar counter and scaring Grillby to half to death when he came in the next morning. Sans was the same as usual, except his puns were……Could he even call them puns anymore? He was pretty sure that the phrase ‘i want to bend you over this table and screw you’ had no pun in it.

Ughhhhhh this is so confusing, Grillby thought for the umpteenth time that week in bed. Why were these two acting so weird? They couldn’t be coming onto him, they were dating!…well, he walked into quite a few heated make out sessions in his back room (how did they even get there anyway!), so he was pretty sure they were dating.

Grillby turned over, fluffing his pillow and relaxing, adamant to stop losing sleep over this until a startling realization hit him.  _What if they were trying to initiate a threesome with him???_

A few hours of speculation left him finally passing out, only for the alarm to wake him up five minutes later.

Sighing hard enough to land a new career in ASMR, Grillby dragged himself to his restaurant, deciding on the way to finally confront the two on these actions.

Luckily, or perhaps unluckily for him, both were waiting for him at the door. For once Papyrus was wearing something weather-appropriate, and Sans was wearing…sneakers?

“Grillby!” “hey grillbz” they chanted in unison as the fire bartender into the building after he unlocked it.

Like ducklings, they followed Grillby through to the back room, idling by the door as he hung up his coat. He went to turn back and address the two brothers, but he was pushed to the wall. Turning his head and opening his eyes, he came face to face with a blushing Papyrus.

“Hey Grillby,” Papyrus giggled, jaw opening just wide enough to show a bright orange tongue. “Pucker up.”

“..wh-mhm!” Grillby was cut off by a sudden kiss, the bright orange tongue sliding into his mouth to tangle with his. Despite himself, he chose to wrap his arms around Papyrus’ waist. Logic be damned, a cute skeleton was kissing him, might as well milk it was all its worth.

However…where was Sans?

As if to answer him, he felt a slight tugging at his waist before the air hit his legs. He broke the kiss, looking down to see the mischievous eyelights of the older brother on his knees. Grillby’s pants were at his feet and Sans was rubbing a hand over the waistband of his boxers, before pulling those down too.

“oh man grillbz, you’re packing some  _heat_  down here, aren'tcha?” Sans ran his tongue across his teeth, making Grillby’s cock ache. “it it alright if i play with this, i’m drooling over here. i’ll make you feel amazing.”

Grillby, losing the last bit of his sanity, nodded. Papyrus scoffed by Grillby’s ear. “Please Sans, there’s no way you can be as good as the Great Papyrus. I’ll show you how it’s done.” He slid down to the ground beside Sans and took hold of Grillby’s dick, licking a long stripe up. Grillby moaned, bracing himself against the wall as Papyrus’ tongue danced along his length.  _Jesus christ he was good at this._

“paps, you’re clearly an amateur, grillbz can’t even feel it. let big bro show you how it’s done, ” Sans quipped, pulling Papyrus off. Before Grillby could get a word out, Sans took Grillby into his mouth all the way to the base.

Moaning, Grillby let his hands rest on the shorter skeleton’s skull as he tried to keep himself together. Sans’ mouth was simply… exquisite. He must’ve conjured something amazing because Grillby was damn sure that the fucking way Sans was performing on his dick was not normal for any monster, especially a skeleton.

Papyrus, jealous at the lack of attention, slid his hands around to Grillby’s butt, teasing his asshole.

“…Oh my god,” Grillby moaned. “I’m getting really close.”

As if on cue, both brothers upped their assault, rubbing and licking him until he came hard down Sans’ throat, cum splashing against his ribs.

Grillby slid down to the floor in a heap, narrowing missing Papyrus as sat down beside Sans, who was chuckling.

“i won, pay up bro.”

Papyrus made a face, before begrudgingly handing over a small stack of cash. “Ugh, it’s only because you can make a throat. I think my seduction technique was better.”

Sans licked a finger, flipping through the money stack. “all that matters is results bro, and as you can see,” he gestured to his covered ribs, “i got ‘em.” Papyrus huffed in anger. “aw bro, don’t be like that…let’s go home so you can give me my other reward.”

Sans grabbed Papyrus’ hand, give Grillby a wink, and teleported away, leaving Grillby alone in a daze.

_… What the fuck?_

**Author's Note:**

> Oops.
> 
> Thanks for reading! Feel free to bother me on tumblr(NSFW blog): :[Sesurescue](http://Sesurescue.tumblr.com)


End file.
